A textile surface covering with foam backing is known from DE-OS 31 04 835 in which the textile surface structure is provided with a carrier layer of open celled plastics material having small pore volume and the foam backing is applied to this carrier layer. Application of the foam backing occurs there to an exact contour in a closed mold, and venting occurs through the carrier layer. Besides an optimal appearance soundproofing should also be effected. Thus, in the sense of sound insulation it is a conventional mass-spring system with foam (or fleece) as a spring and flexible heavy layer in an acoustically optimal setting as an effective mass. These systems are advantageously made as shaped parts, and for use in passenger vehicles are provided with a carpet covering so that overall a carpet-compact-insulating part results (DE-OS 31 04 835).
The physical parameters of the spring and mass are adequately known, for example from DE-AS ZO 06 741, and different manufacturing processes for such carpet-compact-insulating components are part of the general state of the art.
In the course of optimising the material and decreasing the mass (weight) of sound insulation for vehicles, in particular passenger vehicles, many suggestions have been made as to how, despite the reduced use of insulating materials, at least the same noise comfort can be maintained in the vehicle. The potential for saving is determined essentially by the heavy layer, so that the attempts made have concentrated on reducing this heavy layer. However, it has become evident that a physically determined lower limit exists beneath which behaviour as in a conventional mass-spring system can no longer be brought about. Thus on going below this surface mass Loss of noise comfort inevitably occurs. In an earlier prior art document (DE-AS 20 06 741) the lower limit of the surface mass was said to be about 4 to 5 kgm.sup.-2 while today a further reduction down to about 2 kgm.sup.-2 can be justified. This, however, is only possible if the impairment which necessarily results from reducing the surface mass is compensated by greatly improved acoustic properties of the foam. For this purpose so-called visco-elastic foams were dove loped as described in GAHLAU, H., Fortschrittliche Schallisolationen fur Automobile, Stankiewicz-Information No. 130, Dr. Alois Stankiewicz GmbH, 1987.
According to the prior art it is, however, always necessary to manufacture the heavy layer and the spring separately and to combine them with the decorative covering, usually a carpet.